/*
 * Copyright 2007-2008 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package jsr203.sun.nio.fs;

import java.io.IOException;
import java.security.AccessController;
import java.security.PrivilegedAction;
import jsr203.nio.file.FileRef;
import jsr203.nio.file.spi.FileTypeDetector;

/**
 * File type detector that uses GNOME VFS to guess the MIME type of a file.
 */

public class GnomeFileTypeDetector
    extends FileTypeDetector
{
    // true if GNOME VFS initialized
    private static final boolean initialized;

    public GnomeFileTypeDetector() {
        super();
    }

    @Override
    public Result<String> probeContentType(FileRef obj)
       throws IOException
    {
        if (!initialized)
            return null;
        if (!(obj instanceof UnixPath))
            return null;

        UnixPath path = (UnixPath)obj;
        NativeBuffer buffer = NativeBuffers.asNativeBuffer(path.getPathForSysCalls());
        byte[] mimeType;
        try {
            mimeType = probe(buffer.address());
        } finally {
            buffer.release();
        }
        if (mimeType == null)
            return null;

        // assume syntax is correct
        final String result = new String(mimeType);
        return new Result<String>() {
            @Override
            public String get() {
                return result;
            }
            @Override
            public Result.Confidence getConfidence() {
                // LOW confidence as based on file extension rather than content
                return Result.Confidence.LOW;
            }
        };
    }

    // initialize GNOME VFS
    private static native boolean init();

    // probe file, return MIME type or null
    private static native byte[] probe(long pathAddress);

    static {
        AccessController.doPrivileged(new PrivilegedAction<Void>() {
            public Void run() {
                System.loadLibrary("nio");
                return null;
        }});
        initialized = init();
    }
}
